Control valves for various types of plumbing apparatuses are now required by code in many jurisdictions to incorporate anti-syphon features to prevent the contamination and/or pollution of the water supply. This is especially true in the case of household plumbing apparatuses in which a potable water supply is used, such as food or waste disposals which are driven by the pressure of the household water supply. The anti-syphon valve prevents the water which has been discharged by the valve into the waste water system from re-entering and contaminating the water supply by, for example, a drop in pressure in the water supply causing such pressure to be lower than the pressure in the waste system, such as through a break in the water supply main.
Any valve which is used selectively to allow a pressured water supply to drive a food disposal must have selecting means for selectively allowing and preventing the water supply to reach the servo portion of the disposal apparatus. The selecting means must be easy to operate for a homemaker or other person using the disposal, but should be difficult for a child to do so in order to ensure the child's protection against injuring a hand or the like in the disposal. The valve also should incorporate means for venting or bleeding the fluid pressure in the apparatus to atmosphere in order to equalize pressure when the valve is not turned on.
Anti-syphon protected valves have various uses other than in directing pressured water for driving devices, including diverting bath water supply to a shower, placing chemical additives or the like in a fluid flowing from a supply for sterilization or enrichment, filling containers with liquid, and other applications requiring protection from contamination and/or pollution which will be readily apparent to those skilled in the art.
Anti-syphon and vacuum breaker valves which have been developed previously include the valve disclosed in U.S. Pat. No. 4,553,560 to Tucker et al., which describes a valve comprising a central inlet passage with a concentrically surrounding coaxial outlet passage, in which fluid from the inlet passage flows through a ball valve to its top, pushing up a cup-shaped float which seals the top of the inlet passage in the closed position and which directs the fluid into the outlet passage in the open position. The float is guided in its vertical movement by an attached rod sliding in an overlying cover. The ball valve must be accessed from the side and must use a central inlet passage.
Another float valve guided by a sliding rod is disclosed in U.S. Pat. No. 4,635,848 to Little. In both references, the float rises in the open position to seal off vent holes which communicate with the discharge outlet by means of a chamber surrounding the float. A similar sliding rod valve is disclosed in U.S. Pat. No. 2,990,843 to Smith.
Other types of anti-syphon valves are disclosed in U.S. Pat. No. 3,788,342 to Milette et al., which discloses a valve guided in its movement by the inlet passage, and U.S. Pat. Nos. 5,060,687 to Gayton and 5,038,814 to Gayton et al., which disclose valves using flexible diaphrams instead of floats.
Control valves used in water-powered food disposal systems are disclosed in U.S. Pat. Nos. 3,700,178 to Verley and 4,573,642 to Spelber.